In many welding applications, the feeding of a welding wire, i.e. a wire which can be melted to form the weldment (filler wire) or a wire which is used as an electrode to strike the arc, must be monitored with care to ensure, for example, a constant feed rate.
Monitoring devices are provided for this purpose on welding machines and can be a measuring roller or wheel against which the welding wire is displayed and which can be pressed against this wheel by a pressure roller.
The measuring roller or wheel is coupled to a signal generator, usually a pulse generator, which can produce a pulse for each increment or advance of the wire. The number of pulses thus represents the length of wire fed and the frequency or cadence of the pulses, i.e. the number of pulses per unit time, can represent the speed of the wire. Each pulse also represents an increment of angular displacement of the measuring wheel or roller and a constant rate of pulse generation can signal a constant speed of the wire.
If the pulses are counted or otherwise accumulated in a pulse counter, the total value will represent the weld material consumed in a particular process.
Earlier monitoring devices were relatively complex and had a particular problem in that it was difficult to insert the wire into the monitoring device, particularly when the wire had to be threaded through wire guides fore and aft of the measuring roller.
In one conventional system for this purpose, to insert the wire into the guide grooves on either side of the measuring and pressing rollers, it was necessary to loosen a pair of screws which held guide plates in place, to shift these plates until the grooves were exposed, to insert the wire and pass it between the rollers, and to replace the plates and the screws.
This process was time-consuming and had to be repeated each time a fresh length of wire was supplied to the welding site.